The present invention relates generally to the production of radioactive ion beams (RIB) and radioisotopes, and, more specifically, to a connector assembly suitable for use in facilities that have both, high current demands and high cooling demands. In RIB facilities, such as TRIUMF's Isotope Separator and ACcelerator (ISAC) facility, a proton beam can be applied to the target, thereby producing a variety of unstable radioactive nuclei that can be separated and directed to various experimental areas and may be subjected to secondary acceleration.
Radioisotopes may be produced by irradiating a target material with a particle beam produced in an accelerator with the target material and beam particles determining the radioisotope products resulting from a range of nuclear reactions. The desired sample material, which may be provided in gas, liquid or solid form, is placed in a suitably configured target and then irradiated with a specified charged species at a particular beam current and beam energy sufficient to modify the sample material and produce the desired radioisotope product species. The radioisotope product(s) may then be recovered from the altered sample material and/or the target surfaces for use in other applications.
Other research utilizes nuclear reactions for producing radioactive nuclear beams rather than lighter radioisotopes. Radioactive ion beams can be produced with a wide variety of techniques with a common factor being that the isotope(s) of interest is the result of a nuclear reaction, e.g., a reaction between an accelerated primary projectile beam and a stationary target. The list of reactions that are used for RIB experiments includes, for example, fission, fusion-evaporation, spallation, and fragmentation.
Which reaction is chosen depends to a large degree on which radioactive nucleus one wants to produce. As a rule, it is easier to produce “proton rich” nuclei, i.e., those nuclei with a low neutron-to-proton ratio (isospin). Because the initial reaction products often are highly excited immediately after the nuclear reaction, they will deexcite by evaporating particles. Because the average binding energy for neutrons is lower than for protons, neutrons are preferentially evaporated from the reaction products, leaving residues with lower isospin than the projectile/target combination. Accordingly, it can be difficult to produce neutron-rich residues from nuclear reactions, although fission and some fragmentation reactions can be used. In any event, the probability that the bombardment will produce a certain nuclide (the so-called production cross section) tends to decrease with the distance of the desired reaction product from the stability line regardless of the production method utilized.
In most cases, the production reaction is non-selective and produces a variety of reaction products that must be subsequently separated to isolate the desired isotope and provide the necessary degree of isotope purity. The choice of separation method will be limited by the reaction used. If the reaction residues have relatively high kinetic energy, such as those seen in reaction residues from fragmentation processes, they can be separated according to their charge-to-mass ratio by deflection in magnetic and/or electric fields (assuming that at least some electrons were removed to leave the residues in an ionized state.) In other reactions, the reaction residues might have relatively low recoil velocities, in which case isotope separation on-line (ISOL) techniques may be utilized in which the residues are collected (e.g., in a catcher foil or a gas), transported via diffusion or gas-jet techniques into an ion source where they are (singly) ionized, and then extracted by a relatively low acceleration potential. The resulting ion beam can then be electromagnetically mass separated.
One of the more frequent operations associated with the production of radioisotopes is removing or otherwise accessing the target assembly that will be or has been irradiated by the charged particle beam. Particularly during the production of RIB, the target assembly may be fabricated from a refractory metal, thereby allowing the target to be heated to relatively high temperatures. Establishing and maintaining this temperature can demand relatively high power levels, e.g., 1000 A or more, and the target temperature can present problems for adjacent, non-refractory components, such as the electrical connections to the target. The operation of the facility also typically includes detaching (and subsequently reattaching) various power and coolant supply lines required for proper operation of the various parts of the apparatus.
In particular, sufficient cooling capability is required for operating the accelerators at higher beam currents and energies for controlling the temperature of the target and/or adjacent components in order to increase the production of the desired radioisotopes, control pressure increases within the system, avoid heat damage to components and/or maintain the sample material in a desired state. Accordingly, a need exists for simplifying and/or otherwise improving the ability to make the necessary electrical and fluidic connections in such equipment.